The test piece is an acrylic cylinder with a diameter 250mm, height 300mm, and thickness 10mm. On the bottom of the test piece, Four acrylic plates with area 30mm x 30m and thickness 3mm were attached in order to prevent the vibration base from being tightly adhered by the test pieces (Fig.2).
Fig.2. Test piece
3.3 Ballast
The ballast is for adjusting the under-water weight of the test piece. The ballast used in this experiment is made of iron.
3.4 Spring coefficient
The spring coefficient was determined by measuring it 5 times in case the nominal spring coefficient takes the values of 0. 1kgf/cm(1.0N/cm), 5kgf/cm(49.0N/cm), and 10kgf/cm(98.1N/cm) and by taking their mean value. The results are listed in Table 2.
Table 2. Spring coefficients
3.5 Experimental method
To allow the degree of freedom of exclusively mono-directional response displacement of the test piece to be maintained, an acrylic guard was constructed to be attached on both the sides of the test piece. Further more the experiment was conducted following the procedure shown below (Fig.1).
